Apparatus for controlling ignition time of automobile engine



y 1970 YOSHITAMI KASHIWAGI ET AL 3,521,609

APPARATUS FOR CONTROLLING IGNITION TIME OF AUTOMOBILE ENGINE Filed Aug. 29, 1967 I I2 50 O L 22 l .v

I8 2o ,/48 i a4 28 3o 56 United States Patent 3,521,609 APPARATUS FOR CQNTROLLIN G IGNITION TIME OF AUTOMOBILE ENGINE Yosliitanii Kashiwagi and Yasuo Tada, Himeji, Japan, assignors to Mitsubishi Denki Kabushiki Kaisha, Tokyo, Japan Filed Aug. 29, 1967, Ser. No. 664,036 Claims priority, application Japan, Aug. 31, 1966,

41/ 82,093 Int. Cl. F02p 5/04; F0211 31/00 US. Cl. 123117 8 Claims ABSTRACT OF THE DISCLOSURE A carburetor for an automobile engine is provided with two apertures adjacent a throttle valve, one on each side of the valve when it is in its idle position. A pressure responsive device is divided into an atmospheric chamber and a first and a second pressure chamber by first and a second flexible diaphragms with each of the pressure chambers communicating with a respective one of the apertures. A movable control rod extending through the first diaphragm and connected to the second diaphragm for limited relative movement is connected to a support plate for a contact breaker. When the engine accelerates the first diaphragm is arranged to respond to a fuel pressure in one of the apertures to rotate the support plate through the control rod so as to advance the ignition timing of the engine, however, when the engine decelerates the second diaphragm is arranged to respond to a fuel pressure in the other aperture similarly to advance the ignition timing of the engine.

This invention relates in general to an aperture for automatically controlling the point at which an internal combustion engine of an automobile is to be ignited, in accordance with the pressure of a fuel flowing through a feed fuel line to the engine, and more particularly to such an apparatus especially suitable for use in decreasing the amount of undesirable waste expelled from the engine.

It is well known that during the idling and decelerating operations of any automobile internal combustion engine, the wasted gas expelled from the engine generally contains, in large amounts, harmful and undesirable waste such as gaseous hydrocarbons, gaseous carbon monoxide, etc. The results of experiments have confirmed and reported that with an automobile engine operated at a low speed the harmful waste matter and especially gaseous hydrocarbons contained in the waste gas could be limited by setting the timing point of the ignition to an angular position suificiently in advance of the upper dead point of the associated piston. This has been generally accomplished by forcing an advance angle up to approximately 10 degrees provided by a centrifugal and a vacuum advance device to advance to a large angle such as approximately 20 degrees.

For example, the copending US. application Ser. No. 656,580 filed on July 27, 1967, by H. Miyazaki et a1. and assigned to the same assignee as the present application discloses an advance device comprising a single pressure chamber for operating a single flexible diaphragm disposed in a vacuum advance device of conventional construction, and means for selectively introducing a pair of fuel pressures sensed by means adjacent but on opposite sides of a throttle valve in its idle position, which throttle valve is disposed in a feed fuel pipe leading to the associated automobile engine. The device is arranged such that during an acceleration or high speed operation of the engine a fuel pressure sensed on that side of the 3,521,699 Patented July 28, 1970 throttle valve remote from the engine is introduced into the pressure chamber to control an advance angle of from 0 to approximately 10 degrees while during a deceleration or low speed operation of the engine a fuel pressure sensed on the other side of the throttle valve is introduced into the pressure chamber to provide an advance angle of approximately 20 degrees. Because of the selective introduction of a pair of different fuel pressures into the single pressure chamber, the device has been required to be provided with one valve of relatively complicated construction at each inlet to the chamber through which a fuel pressure is applied to the latter. These valves are then required to be relatively small so that they may be disposed in the inlet and in addition they must also be precisely machined to insure that the valves are operated properly. Such precisely machined parts are undesirable from a manufacturing viewpoint because they are relatively expensive to produce.

Accordingly, it is an object of the present invention to eliminate any incomplete combustion of a fuel occurring when an automobile engine is operating at either of a high and a low speed thereby to decrease the contamination of the surrounding air.

It is another object of the present invention to provide a new and improved apparatus for automatically controlling a timing point of the ignition of an internal combustion engine to a precise magnitude required in either the high and a low speed operation of the engine which apparatus is simple in construction and relatively inexpensive to manufacture.

Briefly, the invention accomplishes the above cited objects by the provision of a dual diaphragm type apparatus for automatically controlling the timing point at which an automobile engine is to be ignited, comprising a control rod movable to control the timing point of ignition of the engine, first sensing means adjacent a throttle valve disposed in a feed fuel pipe to the engine to sense a fuel pressure on that side of the throttle valve remote from the engine, second sensing means adjacent the throttle valve to sense a fuel pressure on that side of the throttle valve near the engine, a first flexible diaphragm responsive to the fuel pressure sensed by the first sensing means to move the control rod, and a second flexible diaphragm responsive to the fuel pressure sensed by the second sensing means to move the control rod, the second flexible diaphragm engaging the movable control means so as not to interfere with movement of the control rod due to the first diaphragm.

The invention is to its organization and its mode of operation as well as other objects and advantages thereof will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawing wherein a single figure shows a front elevational view, partially in section, of a contruction in accordance with the teachings of the invention with parts cut away for simplicity of illustration.

Referring now to the drawing, it is seen that within a distributor housing 10 there are disposed a cam 12 rigidly secured on a distributor shaft (not shown) and an apertured support plate 14 having a centrally located opening surround the cam 12 and rotatable in one or the other direction about the axis of the latter. The distributor shaft is adapted to be driven in the direction of the appropriate arrow by the associated internal combustion engine through a gearing, neither of which are shown. Mounted on the support plate 14 is a contact breaker 16 including a cam follower 18 engaging the cam 12 and a movable contact 20 controlled by the cam 12 through the cam follower 18. The movable contact 20 is moved into and out of engagement with a stationary contact 22 as the cam 12 rotates. When the movable contact 20 3 contacts the stationary contact 22, a primary winding of an ingnition coil (not shown) is permitted to be energized by a battery (not shown), however, when the movable contact disengages from stationary contact 22, an ignition voltage is generated across a secondary ignition winding to ignite one of combustion chambers in the engine. The above mentioned components are of a conventional construction and need not be further described.

According to the teachings of the present invention, a pressure responsive device generally designated by the reference numeral 24 is mounted to the outer periphery of the distributor housing 10. The pressure responsive device 24 comprises a three piece housing 26 including a mounting portion rigidly connected to the distributor housing 10 by screws 28, a middle portion in the form of a hollow cylinder and a lower portion in the form of a bowl connected together into a unitary structure as by caulking with a first flexible diaphragm 30 sandwiched in its tensioned state between the upper and middle housing portions and a second flexible diaphragm 32 sandwiched in its tensioned state between the middle and lower housing portions. This it will be appreciated that the first and second diaphragms 30 and 32 divide the interior of the housing 26 into an atmospheric chamber 34, a first pressure chamber 36 and a second pressure chamber 38.

As shown in the drawing, a stopper 40 in the form of an annulus is connected to the internal peripheral wall surface of the middle housing portion or the first pressure chamber 36 and serves to limit an axial flexing move ment of the second flexible diaphragm 32 in one direction, i.e., in the upward direction as viewed in the drawing. The second diaphragm 32 has rigidly secured on the central portion a connector 42 including an axial extension 44 in the form of a hollow cylinder projecting into the first pressure chamber 36 and having its free end portion inwardly and radially folded to provide a shoulder 46. A longitudinally movable control rod 48 extends through the central portion of the first diaphragm 30 until it projects into the interior of the distributor housing 10 where the free end of the rod is connected to the support plate 14 by a pin 50 for the purpose of advancing the timing point of ignition. It is noted that the atmospheric chamber 34 is sealed from the pressure chamber 36. The control rod 48 has formed at the other end an outwardly directed flange 48a inserted into the extension 44 for a relative longitudinal movement limited by the shoulder 46. This permits the first diaphragm 30 to effect a limited movement of the control rod 48 toward the second diaphragm 32 while the latter diaphragm is maintained stationary.

A first compression spring 52 is disposed between the first and second diaphragms 30 and 32 within the first pressure chamber 36 while a second compression spring 54 is disposed between the second diaphragm 32 and the bottom of the second pressure chamber 38. The first and second pressure chambers 36 and 38 are further provided with the respective inlet ports 56 and 58 through which fuel pressures are selectively applied to the chambers as will be described hereinafter.

In the drawing the reference numeral 60 generally designates a carburetor schematically shown as a section of pipe and serving to vaporize a fuel supplied to the engine (not shown). The carburetor 60 includes a passage 62 through which air, at atmospheric pressure, flows into its interior in the direction of the arrow, a Venturi portion 64 into which a fuel injection nozzle 66 opens, and a throttle valve 68 controlled by an accelerator pedal (not shown). The other end of the carburetor 60 is connected to a manifold (not shown) as is conventional in automobile carburetors.

According to the teachings of the present invention the carburetor 60 is provided with a first and a second pressure sensing unit preferably in the form of an aperture extending through its wall on both sides of the throttle valve 68 in its minimum or idle position. More specifically, the first pressure sensing unit or aperture 70 opens into the carburetor adjacent the throttle valve 68 and upstream thereof, as shown in the drawing with respect to a flow of fuel, i.e., on the air intake side of the throttle valve in its idle position. The second pressure sensing unit or aperture 72 opens into the carburetor adjacent the throttle valve 68 and downstream thereof or on that side of the valve, the manifold side, that is closest to the engine with the valve in its idle position. The first and second pressure sensing apertures '70 and 72 communicate with the inlet ports 56 and 58 through a pair connecting pipes 74 and 76, respectively.

The arrangement thus far described is operated as follows: Assuming that the associated engine .(not shown) is in its accelerating or high speed operation in which the associated acceleration pedal (not shown) is depressed to open the throttle valve 68 from its idling position or shown in the drawing to an open position. Under the assumed conditions, both pressure sensing units 70 and 72 will sense fuel pressures higher than a predetermined negative pressure P which may be normally in the order of 400 mm. Hg. By the term negative pressure used herein is meant a pressure less than the atmospheric pressure. As connected, it is noted that the first pressure sensing unit 70 is designed to sense a negative fuel pressure normally ranging from 0 to approximately 400 mm. Hg. in accordance with the extent to which the throttle valve 68 is open, while the second pressure sensing unit 72 is designed to sense a negative fuel pressure ranging approximately from 450 to 700 mm. Hg. for a purpose as will be apparent hereinafter. The fuel pressures thus sensed are transmitted to the first and second pressure chambers 36 and 38 through the connecting pipes 74 and 76, respectively, and the ports 56 and 58, respectively.

According to the teachings of the present invention the first compression spring 52 disposed within the first chamber 36 is made so weak that if the first flexible diaphragm 30 has applied thereto a pressure differential between a pressure higher than the above mentioned negative pressure P and the atmospheric pressure in the atmospheric chamber 34 the spring 52 permits the diaphragm 30 to move or flex toward the second diaphragm against its action while the second compression spring 54 is designed so that if the second flexible diaphragm 32 has applied thereto a pressure equal to the difference between the atmospheric pressure and a pressure less than a predetermined negative pressure P which may normally be in the order of 450 mm. Hg, the spring will permit the diaphragm 32 to move or flex in a direction away from the first diaphragm.

Thus when the first diaphragm 30 is exposed to a fuel pressure up to 400 mm. Hg, a pressure differential between the atmospheric pressure prevailing in the atmospheric chamber 34 and the pressure now present in the first pressure chamber 36 causes the first flexible diaphragm 30 to flex or move toward the second diaphragm 32 to move the control rod 48 in the direction of the arrow a distance determined by the extent to which the throttle valve 68 has been opened or by the particular loading on the engine. This causes the support plate 14 to rotate in the direction opposite to the direction of rotation of the cam 12 to provide an advance angle for ignition, or spark advance, proportional to the loading on the engine.

On the other hand, the second flexible diaphragm 32 is prevented from flexing or moving because the pressure higher than the said predetermined negative pressure P is ineffective for flexing or moving the second diaphragm 32 which has, in turn, app ied to both opposed surfaces the substantially equal fuel pressures prevailing in the first and second pressure chambers 36 and 38, respectively, and because the flanged end portion 48a of the moving control rod 48 is free to move in the interior of the extension 44 which is secured to the second diaphragm, without affecting the latter.

With the engine operated at a slow speed or in its decelerated state, the throttle valve 68 is adjusted to its minimum open or idle position, as shown in the drawing, and permits air and fuel to pass in small amounts therethrough. Under these circumstances, the first pressure sensing unit 70 will sense a fuel pressure approximately equal to the atmospheric pressure while at the same time the second pressure sensing unit 72 will sense a fuel pressure less than the predetermined negative pressure P which may be normally in the order of 450 mm. Hg as above described and which is less than the first predetermined negative pressure P As above described, the second pressure sensing unit 72 is adapted to sense a fuel pressure of from 450 to 700 mm. Hg, and the second compression spring 54 in the second pressure chamber 38 is adapted to respond to a pressure less than the predetermined negative pressure P The fuel pressures sensed by both pressure sensing units 70 and 72 are transmitted to the first and second pressure chambers 36 and 38, respectively, such that a pressure approximately equal to the atmospheric pressure prevails in the first chamber 36 while a pressure less than the predetermined negative pressure P prevails in the second chamber 38. Thus a difference between both pressures is exerted on the second flexible diaphragm 32 to flex or move it away from the first diaphragm 30 as a result of the compression of second spring 54 due to such pressure differential. When the second diaphragm 32 begins to flex it is in the position as shown in the drawing and the flanged end portion 48a of the control rod 48 is engaged with the shoulder 46 of the extension 44. Therefore the flexing movement of the second diaphragm 32 is accompanied by a pulling movement of the control rod 48 in the direction of the appropriate arrow with the result that the timing point of ignition is caused to, or there is a spark advance, advanced in accordance with the particular loading on the engine.

Thus harmful gases such as gaseous hydrocarbons contained in the waste gas decrease in amounts during the high and low speed operations of the engine.

From the foregoing it will be appreciated that the present invention is effective for advancing the timing point of ignition as required during either of the accelerating and decelerating operations of the associated engine by using a pair of flexible diaphragms and a pair of pressure chambers. Also the present invention is very simple in construction and easily manufactured as compared with apparatus utilizing valve devices as previously described.

While the invention has been illustrated and described in conjunction with a single preferred embodiment thereof it is to be understood that various changes and modifications may be resorted to without departing from the spirit and scope of the invention.

What we claim is:

1. In a dual diaphragm type apparatus for automatically controlling the timing point at which an automobile engine is to be ignited, the combination of a control rod movable to control the timing point for the ignition of the engine, carburetor means including a feed fuel pipe having an air intake end and a manifold end, a throttle valve pivotally mounted in the feed fuel pipe between the air intake end and the manifold end, said throttle valve having an idle position in which said throttle valve extends substantially transversely of the feed fuel pipe to provide an air intake side of the throttle valve in its idle position and a manifold side of the throttle valve in its idle position, first sensing means positioned adjacent the throttle valve on the air intake side of the throttle to sense a fuel pressure on that side of the throttle valve, second sensing means positioned adjacent the throttle valve, on the manifold side of the throttle valve to sense a fuel pressure on that side of the throttle valve, a first and a second flexible diaphragm, means for connecting the diaphragms to said control rod, said first flexible diaphragm responsive to the fuel pressure sensed by the first sensing means to move the control rod, said second flexible diaphragm responsive to the fuel pressure sensed by the second sensing means to move the control rod, said connecting means including means for engaging the second flexible diaphragm with the movable control rod so as not to interfere with the movement of the control rod as it is moved by the first diaphragm.

2. A control apparatus as set forth in claim 1, further comprising an atmospheric chamber maintained at substantially an atmospheric pressure, a first pressure chamber to which said fuel pressure sensed on the air intake side of said throttle valve is applied, and a second pressure chamber to which said fuel pressure sensed on the manifold side of said throttle valve is applied, said first flexible diaphragm providing a boundary between said atmospheric chamber and said first pressure chamber, said second flexible diaphragm providing a boundary between said first pressure chamber and said second pressure chamber.

3. A control apparatus as set forth in claim 1, further comprising a first pressure chamber to which said fuel pressure sensed by the first sensing means is applied and which is operatively connected to an atmospheric pressure chamber through said first flexible diaphragm, a second pressure chamber to which said fuel pressure sensed by said second sensing means is applied and which is operatively connected to said first pressure chamber through said second flexible diaphragm, a first compression spring disposed within said first pressure chamber to control flexing movement of said first diaphragm, and a second compression spring disposed within said second pressure chamber to control flexing movement of said second diaphragm, said second compression spring being more resilient than said first compression spring.

4. In a dual diaphragm type apparatus for automatically controlling the timing point at which an automobile engine is to be ignited, the combination of a support plate having mounted thereon a contact breaker, a cam, said contact breaker being controlled by said cam to open and close an ignition circuit for the engine, a movable control rod operative to rotate said support plate about the axis of said cam to control the ignition timing of the engine, carburetor means including a feed fuel pipe having an air intake end and a manifold end, a throttle valve pivotally mounted in the feed fuel pipe between the air intake end and the manifold end, said throttle valve having an idle position in which said throttle valve extends substantially transversely of the feed fuel pipe to provide an air intake side of the throttle valve in its idle position and a manifold side of the throttle valve in its idle position, first sensing means positioned adjacent the throttle valve on the air intake side of the throttle valve to sense a fuel pressure on that side of said throttle valve, second sensing means positioned adjacent said throttle valve on the manifold side of the throttle valve to sense a fuel pressure on that side of said throttle valve, a first and a second flexible diaphragm means for connecting said diaphragms to said control rod, said first flexible diaphragm always engaging said control rod and responsive to the fuel pressure sensed by said first sensing means to move said control rod, said second flexible diaphragm responsive to the fuel pressure sensed by said second sensing means, said connecting means including a coupling member rigidly secured to said second flexible diaphragm, said coupling member being maintained disengaged from said control rod when the control rod is moved through the flexing movement of said first diaphragm, and wherein said coupling member, when said second diaphragm is flexing, engages said control rod to transmit the movement of said second diaphragm to said control rod.

5. A control apparatus as set forth in claim 4, further comprising an atmospheric pressure chamber, a first pressure chamber to which the fuel pressure sensed by said first sensing means is applied, and a second pressure chamber to which the fuel pressure sensed by said sensing means is applied, said first flexible diaphragm providing a boundary between said atmospheric chamber and said first pressure chamber and responsive to a difference in pressures within said atmospheric and first pressure chambers to move said control rod, said second flexible diaphragm providing a boundary between said first and second pressure chambers and responsive to a diflerence between the pressures in said first and second pressure chambers to move said control rod.

6. A control apparatus as set forth in claim 4, further comprising a first pressure chamber to which the fuel pressure sensed by said first sensing means is applied and which is operatively connected to an atmospheric pressure chamber through said first flexible diaphragm, a second pressure chamber to which the fuel pressure sensed by said second sensing means is applied and which is operatively connected to said first pressure chamber through said second flexible diaphragm, a first compres sion spring disposed within said first pressure chamber to control flexing movement of said first diaphragm, and a second compression spring disposed Within said second pressure chamber to control flexing movement of said second diaphragm, said second compression spring being more resilient than said first compression spring.

ment of said second diaphragm, said second spring being capable of exerting a greater force than said first spring.

8. A control apparatus as set forth in claim 5 wherein a first compression spring is disposed within said first pressure chamber to control the movement of said first diaphragm and a second compression spring is disposed within said second pressure chamber to control the movement of said second diaphrgam, said second spring being capable of exerting a greater force than said first spring.

References Cited UNITED STATES PATENTS 3,329,136 7/1967 Cadlou 123-117.1 2,091,924 8/1937 Harmon 123 117.1 2,503,753 8/1950 Mallory 123 117.1 2,596,830 5/1952 Udale 123 117.1 3,027,884 4/1962 Bale et al. 123-117.1XR 3,043,285 7/1962 Bettoni 123 117.1 3,252,450 5/1966 Dietrich etal 123 117.1

FOREIGN PATENTS 514,206 11/1920 France.

7. A control apparatus as set forth in claim 2 wherein WENDELL BURNS Primary Examiner a first compression spring is disposed within said first pressure chamber to control the movement of said first diaphragm and a second compression spring is disposed Within said second pressure chamber to control the move- U.S. Cl. X.R. 123-97 

